[Trogdor2010]

Yes, even the DVI port in most modern graphics card can output audio (as long as you use a DVI-to-HDMI cable you should be fine). AMD (ATI 3000 series or newer) graphics cards are usually plug and play with this implementation, while Nvidia (9000 series or newer) requires you to use the SDPIF output on the card to the motherboard, but shouldn't be too hard to use.

One note, some Nvidia cards may not bitstream DTS-HD or TrueHD (although like the PS3, most current blu-ray software should provide the audio codecs you need. AMD usually does a pretty good job with keeping up as HTPC features, but still check if the cards can bitstream.